Everyone knows of the Sun as the bright power plant at the center of our solar system; its heat warms the surfaces of the innermost planets, and its gravitational forces act as the stellar glue that keeps every world in its respective orbit.
While we’ve uncovered a lot about our Sun by inspecting it up close, it’s still proves challenging to prognosticate our Sun’s future. To help with that, astronomers often study older stars from alien systems to procure clues regarding how stars develop over time.
Image Credit: ALMA (ESO/NAOJ/NRAO)/W. Vlemmings
One such star that could teach us a lot about our Sun’s fate is W Hydrae, an old red giant located almost 320 light years away from Earth. Fortunately, astronomers recently snagged some images of the star’s surface with the Atacama Large Millimeter/Submillimeter Array (ALMA), generating some of the most comprehensive datasets of any star of this caliber to date.
In the journal Nature Astronomy, the researchers detail their complete findings, and what they found taking place within W Hydrae’s chaotic chromosphere piqued their curiosity.
“For us, it's important to study not just what red giants look like, but how they change and how they seed the galaxy with the elements that are the ingredients of life,” elaborated study lead author Wouter Vlemmings from the Chalmers University of Technology.
“Using the antennas of ALMA in their highest-resolution configuration, we can now make the most detailed observations ever of these cool and exciting stars.”
Related: ALMA observes the Sun in a new light
While astronomers have analyzed the surfaces of red supergiant stars previously, W Hydrae captivates more interest because its mass is akin to the Sun’s despite it's larger size; this means that it might provide critical insight into how the Sun will behave once it changes into a red giant at the end of its life cycle.
ALMA's data revealed something that astronomers weren’t expecting to see: a bright spot residing in the star’s chromosphere. It’s indicative of a process that scientists don't account for in current asymptotic giant branch star models, which means the discovery could revolutionize the way we think about these stars forever.
“Our measurements of the bright spot suggest there are powerful shock waves in the star's atmosphere that reach higher temperatures than are predicted by current theoretical models for AGB stars,” said Theo Khouri, a co-author of the study.
Whether shockwaves (or something else) caused the bright spot remains to be seen, but astronomers aren’t relying on a single observation to re-write science textbooks. Follow-up investigations are in planning as of this writing to achieve a better understanding of what’s going on in W Hydrae’s chromosphere.
With a little bit of luck, we might see the same reaction in subsequent observations; perhaps even in other red giants with masses tantamount to the Sun. It should be exciting to see how this research will impact existing theories about our Sun's evolution over millions or billions of years.